The deaths follow another deadly incident at APG's Super Pond in January. The man-made, 150-foot deep Super Pond, formally known as the Unexploded Ordnance Range pond, is used by the military to shock-test marine vessels.

George H. Lazzaro Jr., an engineering technician in the Firepower Directorate of the Aberdeen Test Center, died Jan. 30 while doing routine maintenance on the test infrastructure. His death is still under investigation, and a base spokesman has said the two incidents are "unrelated."

A Harford County emergency response source said that in Tuesday's incident, the divers were in cardiac arrest when they surfaced and had been working in the pond on air hoses and were tethered to each other.

Maj. Gen. Genaro J. Dellarocco, commanding general of the United States Army Test and Evaluation Command, released a statement Wednesday responding to the death of the sailors:

"The US Army Test and Evaluation Command and Aberdeen Test Center are troubled by the loss of two Navy divers February 26 and our personal loss on January 30. Our thoughts and prayers are with Mobile Diving and Salvage Unit Two and the divers' families. We are investigating the cause of this accident in coordination with the Naval Criminal Investigative Service. The Super Pond is currently closed for the investigation. The safety of all personnel working on APG and at the Super Pond is our number one priority."